Adding 3rd Purple Tang, transferring tanks, best way to do it

[gbreef1]

Right now I have 2 purple tangs and scopus that seems to sometimes school with them and other times pretty aggressive so not sure if I am going to move the scopus to the new tank. Anyway one purple tang is huge and the other is pretty big medium/ large. The third one I am going to add is medium/small. They are going to be going to a 300 gallon. Any harm in allowing the smallest one in first and then adding the other two in a few days or week later or is it best to just put them in all at one time?

 

[KorL]

I think either way might work. But best would be to give the smaller tang some time alone to acclimate to the tank.